1. Field of the Invention
The present invention relates to a spindle motor, and more particularly, to a spindle motor of which a rotating member is supported by fluid dynamic pressure generated through the filling of a lubricating fluid.
2. Description of the Related Art
A small spindle motor used in a hard disk drive (HDD) is generally provided with a fluid dynamic bearing assembly, and a bearing clearance formed between a shaft and a sleeve of the fluid dynamic bearing assembly is filled with a lubricating fluid such as oil. The oil filling the bearing clearance may generate fluid dynamic pressure while being pumped, thereby rotatably supporting the shaft.
The bearing clearance may be formed by an upper surface of the sleeve and a lower surface of a rotor hub coupled to the shaft to thereby rotate together therewith. In addition, the bearing clearance formed by the upper surface of the sleeve and the lower surface of the rotor hub may be also filled with lubricating fluid.
Meanwhile, when an impact is applied from the outside, the lubricating fluid may be leaked from the bearing clearance, that is, a side at which an interface between the lubricating fluid and air is formed, to the outside of the bearing clearance.
When the lubricating fluid leaked to the outside is scattered, an inner portion of the spindle motor may be contaminated by the lubricating fluid.
In addition, when the lubricating fluid is leaked to the outside, the fluid dynamic pressure generated through the lubricating fluid may be reduced, thereby deteriorating performance of the spindle motor and reducing a lifespan thereof.